1. Field of the Invention
This invention relates to the field of collecting and preparing cervical smears for diagnostic purposes, and more particularly to a device and method for simultaneously collecting samples of both exocervical and endocervical cells.
2. Description of the Relevant Prior Art
Modern gynecological practice includes routine screening of women for the detection of inflammatory, pre-malignant and malignant changes in the cervix and uterus. Such screening provides the most effective means for early detection and even prevention of uterine cervical cancer. Because such routine screening has proven invaluable, many devices have been invented for obtaining diagnostic samples from the cervical area.
In their article entitled Analysis of Five Sampling Methods for the Preparation of Cervical Smears, Boon et al, Acta Cytologica (1988), pages 843-848, the authors describe five different devices for cervical cytologic sampling, and set forth the results of an analytic study undertaken to determine the efficacy of each device in obtaining acceptable samples. These five prior art devices include: (a) a modified Ayre spatula; (b) a cytological brush called the "Cytobrush" (see U.S. Pat. Nos. 3,881,464 and 4,759,376 for descriptions of such brushes), used in conjunction with the spatula; (c) a device called a "Cytopick," having a tip on one end and a spatula on the other; (d) a moistened cotton swab in combination with the spatula; and (e) a Cervex Brush, such as that described in U.S. Pat. No. 4,700,713.
The referenced article emphasizes that the sampling method utilized has a great impact on the quality of the cervical smear, "a decisive factor in the efficacy of population screening [for uterine cervical cancer.]" According to the article, the presence of endocervical cells is necessary for an adequate smear. The endocervical cells are, characteristically, glandular-type cells, in contrast to exocervical cells, which are squamous cells. As the authors emphasize, some of the sampling methods described are more effective in obtaining the important endocervical cells than are others. In particular, the spatula alone or in combination with the moistened cotton swab fails to produce adequate smear samples due to the absence of endocervical cells. In contrast, both the Cytobrush and the Cytopick exhibited superior performance in obtaining adequate smear samples containing endocervical cells.
It should be noted that most of the devices described in the referenced article were not capable of taking simultaneous samples from both the exocervix and the endocervix. The spatula, for example, is used by rotating it on the ectocervix. It does not penetrate the cervical os to any significant degree and, hence, does not sample the endocervix. The Cytobrush and Cytopick tip penetrate the cervical os to obtain endocervical samples. In order to obtain exocervical samples, either a separate device such as a spatula or a spatula disposed on the other end of the Cytopick must be used. Likewise, the relatively ineffective cotton swab is used to penetrate the endocervix, but does not provide an exocervical sample.
Of the methods described in the referenced article, only the Cervex Brush simultaneously samples both the exo and endocervix. This is possible because the individual bristles of the Cervex Brush are arranged roughly radially and parallel to the stem of the device. The bristles have at least one longitudinal sharp edge. By inserting the brush, the center bristles penetrate the cervical os and scrape the wall of the endocervix, while the outer brushes remain outside the cervical os and abut the exocervical wall, scraping the surface thereof to provide simultaneous exo and endocervical samples. However, as reported in the afore-referenced article, the Cervex brush achieved only moderate results in obtaining endocervical cell samples. This may be attributable to the fact that the bristles of the Cervex brush are relatively thick and tend to collect excess mucous which obscures all samples. Furthermore, this brush does not penetrate the full 2 cm depth of the average endocervix and because of its shape, does not contact and sample the wall of the encocervical canal.
Other prior art devices are known which are designed to effectively obtain endocervical cell samples. For example, the so-called "Bayne Brush" of U.S. Pat. No. 4,762,133 shows, in a preferred embodiment, two brushes attached to the end of the handle, the two brushes projecting at right angles from each other. One brush is inserted into the endocervix, while the perpendicular brush remains outside the cervical os. The device is rotated, thereby causing the bristles of the first brush to sweep the inside of the endocervix and collect cells therefrom, and the second brush to scrape the surface of the exocervical wall, thereby obtaining exocervical cells simultaneously. While the device is, admittedly, effective in obtaining adequate cervical smears, it has a number of drawbacks. First, the relatively rigid bristles of the two brushes often cause bleeding, which results in obscure slides and imperils the accuracy of the results. Furthermore, atypical and immature cell groups may be present in cytobrush smears since this brush tends to remove immature cells from deeper layers of cervical tissue. These cells are not readily recognized by cytotechnicians and can lead to confusing and inaccurate diagnostic reports and may necessitate further invasive procedures. In fact, the medical profession has come to recognize the "brush effect" wherein atypical cells are noted in collected samples but cannot be correlated with any lesions of the cervix. Additionally, the Bayne Brush is complex in construction and relatively expensive. Despite these disadvantages, the Bayne Brush has met with some acceptance in the gynecological field.
Another cervical brush is described in U.S. Pat. No. 4,127,113. This patent describes a device with a rigid stem having a handle at one end and an integral brush disposed on the other end. The brush has a flexible spine and fine, flexible bristles which extend in a row along the spine of the brush. There is a flat blade at the root of the spine which serves as a locator and stop at the entrance to the cervix. The device is inserted into the cervix up to the stop, and rotated so that the brush accumulates sample material from substantially the entire inner wall of the endocervix. The brush is subsequently wiped across a slide to deposit the sample for examination.
As described and disclosed in U.S. Pat. No. 4,127,113, the cervical brush does not provide any structure for simultaneously obtaining an exocervical sample. The flat blade merely serves as a stop; it is not wiped across the slide. Yet, an adequate cervical sample should contain "cells from the squamous epithelium of the vaginal portion of the cervix, from the squamocolumnar junction (also known as the transformation zone), and from the endocervical epithelium." The Papanicolaou Test for Cervical Cancer Detection--a Triumph and a Tragedy, Leopold G. Koss, M.D., JAMA (1989), page 737, 738. Hence, in order to obtain an adequate smear, it would be necessary to use the cervical brush of the referenced patent in conjunction with another device, such as a spatula, for obtaining exocervical cells. This dual procedure is, obviously, time consuming, inefficient and uncomfortable for the patient. Furthermore, significant drying of the first sample can occur during the time the second sample is being prepared resulting in an inaccurate or unreadable slide.
It would be desirable to provide a cervical sampling device which is capable of simultaneously and effectively obtaining samples of both endocervical and exocervical cells.
It would also be desirable to provide such a device which is inexpensive and unitary in construction, which does not cause bleeding in the patient, and which is comfortable for the patient during insertion and use.